[time-nuts] TAPR TICC boxed
attila at kinali.ch
Mon Apr 3 05:22:14 EDT 2017
On Mon, 3 Apr 2017 15:05:55 +1200 (NZST)
Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
> For even more fun you could try to detect the PTFE phase change at around 20C using a cable with PTFE dielectric.
This will require several 100 meters of cable to be measureable with
the TICC. Modern cables are all <500ppm/K, good cables <10ppm/K, phase
stable cables reach even <1ppm/K. Measuring a change of 10ppm with
a resolution of 60ps means that the delay has to be in the order of 6µs,
which is close to 1000m of cable. Even if dithering gives another facor
of 10, this still means 100m of cable.
For this level of comparison I would suggest to use a sinusoidal signal,
instead of a pulse, and do phase comparison, which gives a resolution
in the order of 1ps with very little effort, thus reducing the required
cable length to 10-20 meters.
 "Temperature Stability of Coaxial Cables", Czuba and Sikora, 2011
It is upon moral qualities that a society is ultimately founded. All
the prosperity and technological sophistication in the world is of no
use without that foundation.
-- Miss Matheson, The Diamond Age, Neil Stephenson
More information about the time-nuts